**3. Simulation results**

The HGHE mainly relies on the temperature difference between the fluid in the pipe and the soil outside the pipe for heat transfer, so the temperature of the fluid in the pipe will directly affect the heat transfer process of the buried pipe, and the temperature of the fluid in the pipe is determined by the inlet water temperature. Therefore, this chapter focuses on studying the influence of different inlet water temperatures on the heat transfer characteristics of the HGHE and the soil thermal response. According to the relevant provisions of the specification *Water (Ground) Source Heat Pump Unit (GB/T 19409-2013)* and combined with the actual project, four different inlet water temperatures (32, 35, 38, and 41°C) were selected at equal intervals to conduct the simulation research. The spiral tube flow rate was 170 L/h, and the continuous operation was simulated for 120 h. The variation characteristics of soil temperature field and heat flux per unit pipe length with time were analyzed.
